Desk clerks at the Four Seasons Hotel in Westlake Village, Calif., asked Nissan’s western region public relations representative, Jannelle Grigsby, if she was in a band. During check-in, they noticed the huge case with her luggage, and they logically concluded that it might contain a sizable musical instrument.

The answer was no. Instead, the case contained the only spare windshield in existence for the Nissan GT-R50 by Italdesign prototype car. The case traveled with Grigsby as the $1.5 million car made its way from the Monterey Car Week festivities in Pebble Beach to Los Angeles before Nissan shipped it, and the case, to Japan for the next stop on the vehicle’s world tour.

Based on a Nissan GT-R Nismo, the GT-R50 by Italdesign boasts custom bodywork, a bespoke interior, and a performance massage.

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Grigsby shared this story with me as I waited in the equivalent of an automotive green room for my scheduled hour with the GT-R50. Nissan had invited a handful of local L.A. journalists to drive this high-performance prototype on the fabled roads draped across the Santa Monica Mountains, and I’d made the list.

Allotted 60 minutes with the handcrafted car, my time behind the wheel included a specific route, the man personally responsible for the car riding shotgun, and a chase vehicle behind us.

Lucky for me, the planned route included roads I know well, which meant I could focus on what its like to drive the GT-R50 rather than on the road.

The most dramatic departure from the current GT-R’s design is evident around back, where a tiny window, towering wing, and cylindrical afterburner-style taillights give the GT-R50 a bespoke appearance.

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Commemorating the 50th anniversaries of both the Nissan GT-R and Turin-based design and engineering Italdesign, the GT-R50 is a custom-bodied GT-R that debuted at the 2018 Goodwood Festival of Speed in Chicester, England. Nissan designers in the U.S. and Europe penned the bodywork, and Italdesign translated it from fantasy to reality.

Clearly recognizable for what it is, the GT-R50 is at the same time clearly different from what it is. And that difference extends beyond its exclusive two-tone Liquid Kinetic Gray and Energetic Sigma Gold paint job.

Starting with a GT-R Nismo, Italdesign rebodied the car and reworked the interior using plenty of carbon fiber, Alcantara suede, and premium Italian leather. The GT-R50 also gets a mechanical massage, its hand-built twin-turbocharged 3.8-liter V6 expected to generate 710 horsepower and 575 lb.-ft. of torque in this vehicle. Revised suspension tuning and upgraded braking components are also along for the ride.

Nissan is taking the GT-R50 to driving enthusiast events around the world in order to gauge interest in and viability of a limited-production run of 50 individually tailored examples for customers with lots of money to spend.

“One million starts the conversation,” I’m told. Following the GT-R50 by Italdesign’s appearance in Pebble Beach, Automotive News reported that approximately 400 hand-raisers have already indicated a willingness to part with seven figures to own one.

Perhaps I’m not fully grasping the rarity and importance of the opportunity before me. Making my way out to the GT-R50, the journalist who just returned with the car asks me to snap a photo of him behind the wheel, as evidence that he drove it. I take the picture, and then he offers to take one of me. I decline.

The doors work just like a standard GT-R’s, and I climb aboard, snugging myself into stiffly bolstered yet opulently upholstered performance seats complete with racing harness pass-throughs.

Immediately, it is clear that this is no standard-issue GT-R. Everything is covered in either Alcantara or carbon fiber, and aside from the climate control system panel there is scant evidence of the production car on which the GT-R50 is based. The chopped roof adds intimacy and changes perspective, and narrow fixed side mirrors further restrict outward visibility.

“Are those adjustable?” I ask, firing the twin-turbo V6 and waiting a moment before shifting the 6-speed dual-clutch transmission into gear. They aren’t, which means that I’m going to need to lean forward before making any lane changes during the drive. And because the adjustable rear wing is in a fixed position, it perfectly blocks what little view is available through the back window.

It doesn’t take long to discover two things. First, this GT-R50 prototype is exactly that: a prototype. The hand-built, one-off show car lacks a degree of polish and exhibits a bit of fragility in comparison to its production-spec counterparts. Second, near as I could tell, it drove just like a standard-issue GT-R Nismo.

“This car is making about 650 horsepower,” the car’s handler tells me, explaining that the prototype isn’t tuned to production-intent specification. Not that it matters, of course, because the GT-R50 Prototype is explosively fast with or without the full stable of horses.

Nissan will massage a production version of the GT-R50 by Italdesign to make about 710 horsepower, supplying absolutely ludicrous speed.

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Digital instrumentation conveys metric information, so I’m on my own with regard to estimated speed on the suburban boulevards comprising the first portion of the driving route.

Three toggle switches sit above a gaping center air vent, but, as I discover when attempting to use the one that theoretically controls the Damptronic suspension settings, they’re for show, non-functional in this prototype vehicle.

A Ford F-150 is shadowing the car. I can see just a portion of its enormous chrome grille in the slit of a right-side mirror, and I need to get over to make a turn. With a thwap of the downshift paddle followed by a flick of the turn signal lever (one of the few bits and pieces to have come from the Nissan parts bin), I’ve easily dispatched the Ford.

Now, the road narrows and winds up into the mountains. This is a difficult route, one with chassis flexing camber changes, blind hairpin corners, occasional instances of rockfall, and often non-existent shoulders, leaving little margin for error.

Making matters worse, it’s beer o’clock on a Friday afternoon before a long holiday weekend, and I know from experience that this road turns into a racetrack for contractors leaving gigs at the multi-million dollar mansions dotting the mountainsides, driving their Silverados down into town like they’re channeling Dale Earnhardt Jr.

But, the GT-R50 by Italdesign is insured for $1.5 million, and this route is “insurance approved,” so I get after it. That is what I’m here to do, after all.

As is true of any Nissan GT-R, the prototype delivers a mechanical, raw, and visceral driving experience, one enhanced by its creaking and flexing handcrafted nature, partially dialed tuning traits, and more restrictive visibility. A faint smell of exhaust has replaced the scent of the cabin’s rich materials, which is not uncommon with a prototype vehicle designed primarily for show instead of go. Personally, I welcome it.

Up ahead, a brown decade-old Honda Civic followed by a silver current-gen Toyota Corolla are trundling up the mountain in the same direction I am but at a far slower rate of speed, and the fun comes to an end. Seriously, you could not think of two more appropriate mood killers than the econo-boxes blocking my path to automotive bliss.

And there’s nowhere for them to pull over to let me pass, and nowhere for me to pull over and wait for open road.

Ugh.

Of the GT-R50 by Italdesign’s styling flourishes my favorite is the taillights protruding from the bodywork from beneath the adjustable wing spoiler.

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Eventually, I get another opportunity to exercise the GT-R50 by Italdesign, mindful, of course, that this is a prototype vehicle that, if wrecked, cannot be replaced. No pressure there, eh? But the brief bursts of speed don’t teach me anything meaningful about the car’s enhanced performance compared to the GT-R Nismo on which it is based.

Rather, during this particular drive on these particular roads, it is the prototype’s bespoke cabin, its unique roofline, its narrow side mirrors, and its completely blocked rear visibility that convey exclusivity from behind the wheel. That, and that fact that no matter where you drive it, it draws attention like Ariana Grande with her back to a nearly drooling geezer.

Thickening holiday traffic broke just long enough for me to scream the GT-R50 around one of my favorite freeway on-ramps and onto the 101 freeway north. Two guys in a Toyota Tacoma immediately give chase as I thread the prototype across packed lanes to experience a last burst of glory before turning the car over to the next person. Exiting the highway, the Tacoma passes on the left, the truck passenger’s phone recording the evidence.

Given that no more than 50 examples of the GT-R50 by Italdesign will be built for marque devotees and rare supercar aficionados around the world, that smartphone footage might as well depict an unidentified flying object.

Except this flying object is clearly identifiable as the most powerful and exclusive Nissan GT-R ever created.